Hypoxic Postconditioning Promotes Angiogenesis After Ischemic Stroke

Although hypoxic postconditioning (HPC) has a protective effect on ischemic stroke, its effect on angiogenesis after ischemic stroke is still unclear. This study was designed to investigate the effects of HPC on angiogenesis after ischemic stroke and to preliminarily study the mechanism involved. Oxygen-glucose deprivation (OGD)-intervened bEnd.3 (mouse brain-derived Endothelial cell. 3) was used to simulate cerebral ischemia. Cell counting kit-8 (CCK-8), Cell BrdU proliferation, wound healing, Transwell and tube formation assays were used to evaluate the effect of HPC on the cell viability, proliferation, migration (horizontal and vertical migration), morphogenesis and tube formation of bEnd.3. A middle cerebral artery occlusion (MCAO) model was made in C57 mice to simulate focal cerebral ischemia. Rod rotation test, corner test, modified neurological severity score (mNSS), and balance beam walking test were used to evaluate the effect of HPC on the neurological impairment of mice. Immunofluorescence staining was used to evaluate the effect of HPC on angiogenesis in mice. The angiogenesis-related proteins were evaluated and quantified using western blot. Results showed that HPC significantly promoted proliferation, migration and tube formation of bEnd.3. HPC significantly reversed the neurological deficit of MCAO mice. Moreover, HPC significantly promoted angiogenesis in the peri-infarct area, and angiogenesis was found to be positively correlated with the improvement of neurological impairment. The HPC mice showed higher PLCλ and ALK5 than did MCAO. We conclude that HPC improves the neurological deficit caused by focal cerebral ischemia by promoting angiogenesis. Furthermore, the effect of HPC on improving angiogenesis may be related to PLCλ and ALK5.